From 152272dcb136e4757caf918f89c4888f0fab3ff6 Mon Sep 17 00:00:00 2001
From: Lam Haoyin <root@eatswap.org>
Date: Tue, 15 Feb 2022 11:57:08 +0800
Subject: [PATCH] add: 220215-CN

---
 2202/220215.cpp     | 27 +++++++++++++++++++++++++++
 2202/CMakeLists.txt |  2 +-
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 2202/220215.cpp

diff --git a/2202/220215.cpp b/2202/220215.cpp
new file mode 100644
index 0000000..a79fb0d
--- /dev/null
+++ b/2202/220215.cpp
@@ -0,0 +1,27 @@
+#include <vector>
+#include <iostream>
+#include <unordered_set>
+
+/**
+ * 136. Single Number
+ * Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.
+ * You must implement a solution with a linear runtime complexity and use only constant extra space.
+ */
+
+class Solution {
+public:
+	static int singleNumber(const std::vector<int>& nums) {
+		std::unordered_set<int> s;
+		for (int i : nums)
+			if (s.count(i))
+				s.erase(i);
+			else
+				s.insert(i);
+		return *s.begin();
+	}
+};
+
+int main() {
+	std::cout << Solution::singleNumber({4,1,2,1,2});
+	return 0;
+}
diff --git a/2202/CMakeLists.txt b/2202/CMakeLists.txt
index 3ea8ac5..7d0ba3b 100644
--- a/2202/CMakeLists.txt
+++ b/2202/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(2202)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2202 220215-CN.cpp)
+ADD_EXECUTABLE(2202 220215.cpp)